The present invention relates to an image forming apparatus using electrophotography, and a cleaning blade provided in the image forming apparatus.
In a general electrophotographic image forming apparatus, a surface of a photosensitive drum as an image bearing body (or an electrostatic latent image bearing body) is uniformly charged by a charging roller. Then, the surface of the photosensitive drum is exposed with light emitted by an electrostatic latent image writing device such as an LED head, and an electrostatic latent image is formed. The electrostatic latent image on the photosensitive drum surface is developed with a toner by, for example, a developing roller as a developer bearing body, and a toner image as a developer image is formed on the photosensitive drum. The toner image is transferred to a sheet as a medium by, for example, a transfer roller as a transfer member. The toner and external additives thereof which are not transferred to the sheet and remain on the photosensitive drum are removed by a cleaning member. Recently, in order to enhance image quality (i.e., image definition) and to increase printing speed, a toner having a small particle diameter and a low melting point has come into use. Further, in order to maintain cleaning performance of the cleaning member, it has been proposed to specify a loss elastic modulus of a cleaning blade as the cleaning member (see, Japanese Laid Open Patent Publication No. 2006-171546).
However, even when the loss elastic modulus of the cleaning member is specified, there may be cases where the external additives or the like of the toner may pass through the cleaning blade, depending on a use environment temperature. In such a case, excellent image quality cannot be obtained.